Cup containers have many use applications as simple, disposable containers in various fields of foods and beverages including coffee, juice, yogurt, and the like (See, for example, Patent Document D1). FIG. 12 is a front view, with a right half in a vertical section, of a typical example of a conventional cup container. The cup container 101 as a whole has a cylindrical shape with a bottom. At a lower end of a peripheral sidewall 103 in a cylindrical shape, the sidewall 103 is connected to the bottom 106. At an upper end of the peripheral sidewall 103, a brim-like flange 116 surrounds an upper edge of the sidewall 103.
After the cup of this type has been filled with a content fluid, such as coffee, the cup is usually completed when an upper opening of the cup is sealed by adhering a rim portion of a round seal film 119 to an upper surface of the flange 116, as shown in FIG. 12. The consumer peels off the seal film 119 to sip the content fluid directly, or stabs a straw into the seal film 119 to suck up the drink. The flange 116 serves partly for sealing, partly for performing a function of controlling deformation of the upper opening, and partly as a portion with which support claws come in contact to retain the posture of the cup container in a cup-supplying device in the equipment for filling the cups with a content fluid (hereinafter referred to as the support portion). The flange 116 is also used to hold the cups in a transfer retainer of the filling equipment, and thus, is indispensable for the containers of this type.
The cup container products of this type filled with a content fluid may be sold by heating them in a heater or a microwave oven under the condition that the upper opening has been sealed as described above, or the users themselves may heat a sealed cup container to have a hot drink.